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Kariyawasam GK, Richards JK, Wyatt NA, Running KLD, Xu SS, Liu Z, Borowicz P, Faris JD, Friesen TL. The Parastagonospora nodorum necrotrophic effector SnTox5 targets the wheat gene Snn5 and facilitates entry into the leaf mesophyll. THE NEW PHYTOLOGIST 2022; 233:409-426. [PMID: 34231227 PMCID: PMC9291777 DOI: 10.1111/nph.17602] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 06/27/2021] [Indexed: 05/11/2023]
Abstract
Parastagonospora nodorum is an economically important necrotrophic fungal pathogen of wheat. Parastagonospora nodorum secretes necrotrophic effectors that target wheat susceptibility genes to induce programmed cell death (PCD). In this study, we cloned and functionally validated SnTox5 and characterized its role in pathogenesis. We used whole genome sequencing, genome-wide association study (GWAS) mapping, CRISPR-Cas9-based gene disruption, gain-of-function transformation, quantitative trait locus (QTL) analysis, haplotype and isoform analysis, protein modeling, quantitative PCR, and laser confocal microscopy to validate SnTox5 and functionally characterize SnTox5. SnTox5 is a mature 16.26 kDa protein with high structural similarity to SnTox3. Wild-type and mutant P. nodorum strains and wheat genotypes of SnTox5 and Snn5, respectively, were used to show that SnTox5 not only targets Snn5 to induce PCD but also facilitates the colonization of the mesophyll layer even in the absence of Snn5. Here we show that SnTox5 facilitates the efficient colonization of the mesophyll tissue and elicits PCD specific to host lines carrying Snn5. The homology to SnTox3 and the ability of SnTox5 to facilitate the colonizing of the mesophyll also suggest a role in the suppression of host defense before PCD induction.
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Affiliation(s)
| | - Jonathan K. Richards
- Department of Plant Pathology and Crop PhysiologyLouisiana State University – Agricultural CenterBaton RougeLA70803USA
| | - Nathan A. Wyatt
- Cereal Crops Research UnitUnited States Department of Agriculture‐Agricultural Research ServiceEdward T. Schafer Agricultural Research CenterFargoND58102USA
| | | | - Steven S. Xu
- Cereal Crops Research UnitUnited States Department of Agriculture‐Agricultural Research ServiceEdward T. Schafer Agricultural Research CenterFargoND58102USA
| | - Zhaohui Liu
- Department of Plant PathologyNorth Dakota State UniversityFargoND58102USA
| | - Pawel Borowicz
- Department of Animal SciencesNorth Dakota State UniversityFargoND58102USA
| | - Justin D. Faris
- Cereal Crops Research UnitUnited States Department of Agriculture‐Agricultural Research ServiceEdward T. Schafer Agricultural Research CenterFargoND58102USA
- Department of Plant ScienceNorth Dakota State UniversityFargoND58102USA
| | - Timothy L. Friesen
- Department of Plant PathologyNorth Dakota State UniversityFargoND58102USA
- Cereal Crops Research UnitUnited States Department of Agriculture‐Agricultural Research ServiceEdward T. Schafer Agricultural Research CenterFargoND58102USA
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Sung YC, Outram MA, Breen S, Wang C, Dagvadorj B, Winterberg B, Kobe B, Williams SJ, Solomon PS. PR1-mediated defence via C-terminal peptide release is targeted by a fungal pathogen effector. THE NEW PHYTOLOGIST 2021; 229:3467-3480. [PMID: 33277705 DOI: 10.1111/nph.17128] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 11/24/2020] [Indexed: 05/22/2023]
Abstract
The effector SnTox3 from Parastagonospora nodorum elicits a strong necrotic response in susceptible wheat and also interacts with wheat pathogenesis-related protein 1 (TaPR-1), although the function of this interaction in disease is unclear. Here, we dissect TaPR1 function by studying SnTox3-TaPR1 interaction and demonstrate the dual functionality of SnTox3. We utilized site-directed mutagenesis to identify an SnTox3 variant, SnTox3P173S , that was unable to interact with TaPR1 in yeast-two-hybrid assays. Additionally, using recombinant proteins we established a novel protein-mediated phenotyping assay allowing functional studies to be undertaken in wheat. Wheat leaves infiltrated with TaPR1 proteins showed significantly less disease compared to control leaves, correlating with a strong increase in defence gene expression. This activity was dependent on release of the TaCAPE1 peptide embedded within TaPR1 by an unidentified serine protease. The priming activity of TaPR1 was compromised by SnTox3 but not the noninteracting variant SnTox3P173S , and we demonstrate that SnTox3 prevents TaCAPE1 release from TaPR1 in vitro. SnTox3 independently functions to induce necrosis through recognition by Snn3 and also suppresses host defence through a direct interaction with TaPR1 proteins. Importantly, this study also advances our understanding of the role of PR1 proteins in host-microbe interactions as inducers of host defence signalling.
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Affiliation(s)
- Yi-Chang Sung
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Megan A Outram
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Qld, 4072, Australia
| | - Susan Breen
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Chen Wang
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Bayantes Dagvadorj
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Britta Winterberg
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Qld, 4072, Australia
| | - Simon J Williams
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Peter S Solomon
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
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